Video security systems include security cameras and are often used for surveillance and video data analysis. These security systems are used to monitor buildings, lobbies, entries/exits, and secure areas within the buildings, to list a few examples. Additionally, the security systems are also used to monitor public areas such as garages, parking lots, building exteriors, and other areas in or around the buildings. Generally, these security systems are implemented to monitor usage but also to identify illegal activity such as theft or trespassing, to list a few examples.
Modern video security systems have the capability to analyze the video data captured by the security cameras. Typically, these systems are able to track individuals and possibly notify security personnel if unauthorized persons are entering (or exiting) a restricted area, for example. Additionally, the security systems also monitor objects within scenes. For example, abandoned objects (e.g., unattended backpacks or packages) should be identified in airport terminals, stadiums, or convention centers, for example. On the other hand, security personnel should be notified if objects are removed from a museum or if merchandise is removed from a retail establishment.
Abandoned or removed objects in scenes are identified using an analysis system. It analyzes the video data from the security cameras to generate a background model. The background model may be, for example but not limited to, a single video frame occurring prior to the background change, or an analysis of frames over time. Then current frames of video data from those security cameras are compared against the background model to identify changed pixel patches.
In one example, changed pixel patches were identified and used to mask a changed area in the current frames of video data relative to the background model. These changed pixel patches were used by the analysis system to conclude whether some part of the scene, such as an object in the scene, had changed. Next, the analysis system detected the number of edges in the changed area of the current frame and the background model. If there were more edges in the current frame than the background model, then the analysis system concluded that an object had been abandoned in the scene. In contrast, if there were fewer edges detected in the current frame than in the background model, then the analysis system concluded that an object had been removed from the scene.
In another example, the analysis system measured similarities between content inside and outside of the changed pixel patches in the current frame of video data. If the similarities were above a predefined threshold, then the analysis system concluded the object had been removed from the scene. Conversely, if the similarities of the content were below the predefined threshold, then the analysis system concluded the object had been abandoned in the scene.
In another example, the analysis system analyzed contours around the changed pixel patches in the current frame of video data. Then the analysis system compared the contours of the changed pixel patches to the edges detected in masked areas of the current frame. For each pixel patch or group of patches corresponding to an object, if similarities between the detected edges and the contours exceeded a predefined threshold, then the analysis system concluded that the object had been abandoned in the scene. If the similarities between the detected edges and the contours did not exceed the predefined threshold, then the analysis system concluded that the object had been removed from the scene.